Usability improvement: make it so that whatever tab you chose last is the one selected on the next archetype.
Fix terminology flattening so that term definitions for (say) id9.1 and id92 don't cause removal of def of id9, even though id9 may not be used directly in the (specialised) archetype.
Correct congruence evaluating condition so that if occurrences or sibling_id are Void on child, congruence is True
Remove junk occurrences statements from legacy archetypes
Usability improvement - make it so that flat or diff view stays when chosen across archetypes.